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There's the Rut...

Posted: September 6, 2016

...and then there is breeding.
Locations of a Male 8111 and Female 8403 on October 2, 2014

Locations of a Male 8111 and Female 8403 on October 2, 2014

A recent scientific paper studied buck movement behavior according to age of the male and stage of the rut (early , peak, and late rut). The hypothesis was that males should employ efficient search strategies and periodically check on females to see if they are in estrus.

Because females are in estrus for only about 24 hours, it would behoove a love-stricken male to find the love of his life (at least for that day!) in a timely manner.  Because after that, she is no longer the love of any buck’s life (and she’ll have to wait another 28 days until she is again). 

Females reduce their home range size during the rut  so that it’s easier for males to find them.

The study conducted in Texas observed the movements of 102 males. However, they did not have any females radio-collared.  They had to assume that certain patterns of movements observed were due to breeding events.

In our study we have both males and females radio-collared.  So we did a little data mining to see if these movement patterns could be seen in our deer. Unfortunately, we don’t have all the deer in an area radio-collared, but we do have a number of males and females with overlapping home ranges.

Males are bouncing around like ping pong balls during the rut.  Could we detect potential breeding event looking at the movements of a radio-collared male and female?

Enter Male 8111 and Female 8403 from Potter County. 

First, I made a graph that shows the distance (in meters) between this male-female pair for every location that was obtained. A value near zero means the pair are very close together.

During October and most of November we get locations every 3 hours. Then just before deer season, we get a location every 20 minutes. Hence, a lot more locations beginning about the 25th of November.

Separattion distance between a male and female

So what dots are important?

We know that most breeding occurs the last week of October through November . So we are looking for clusters of points near zero, which would suggest this Mr. 8111 and Ms. 8403 had a date.

Are there any clusters of points near zero, especially during the rut?

Around the 9th of October there are a few points near zero. Then around the 15th of November there is another cluster.  And finally, a third cluster of points close around the 26th of November.

We all know a picture is worth a thousand words.  So a movie is worth a million. The Ms. 8403 is in pink and Mr. 8111 is blue (yes, we are gender identifying). Watch the movements around the 9th of October and 15th and 26th of November.

Could any of those be a possible breeding event? My money is on the 15th of November, but your guess is as good as mine. Those two deer were VERY close together from about 9am on the 15th until about 9am on the 16th.  Hmmmmm….very suspicious….about 24 hours. Coincidence? Probably not!

Of course, there are other non-radio-collared deer in the areas.  We know what Mr. 8111 movements look like when he is close to a female (during the peak of the rut), are there another series of movements during the month of November that might betray him as being with another lover?  

Maybe.  We are still looking at other male-female pairs during the rut.  We’ll let  you know if we figure it out.

-Duane Diefenbach and Jeannine Fleegle

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